Dione Simulation
This is a simulation of what one would expect to find on a terraformed Dione, using formulas from Math And Terraforming. Please note that not even the supercomputers at NASA can provide us with a perfect simulation. The information showed here is only an approximation. Basic data *Distance from Sun: 1453.53 million km *Distance from Saturn: 0.378 million km *Diameter: 1123 km *Solar Constant: 0.0209 *Mass: 0.0001834 Earths *Mean density: 1.478 kg/l *Saturn's period: 29.457 Earth years *Day length: 2.737 Earth days *Rotation axial tilt: 17 degrees to the ecliptic Atmosphere See Atmosphere Parameters Given the very low gravity, it will be difficult for Dione to hold an atmosphere. During this simulation, we will use an atmosphere with the same pressure at sea level as Earth's and a similar composition. *Atmosphere stability for oxygen molecules: **Earth's gravity (15 degrees C): 4.116 **Dione's gravity (15 degrees C): 90.22 **Dione's gravity (0 degrees C): 85.52 **Dione's gravity (-150 degrees C): 38.56 *Atmosphere stability for water molecules: **Earth's gravity (15 degrees C): 7.320 **Dione's gravity (15 degrees C): 160.4 **Dione's gravity (0 degrees C): 152.0 **Dione's gravity (-150 degrees C): 68.55 *Atmosphere stability for hydrogen molecules: **Earth's gravity (15 degrees C): 65.88 **Dione's gravity (15 degrees C): 1443 **Dione's gravity (0 degrees C): 1368 **Dione's gravity (-150 degrees C): 616.9 notes: A value below 10 means stability for over a million years, a value between 10 and 100 means stability between 0.1 and 10 millions of years, while a value higher then 100 means stability for less then 10 thousand years. This calculation does not include solar wind erosion. Dione might be terraformed in a different way, with an average temperature around 0 degrees (see below). Conclusion: The atmosphere of Dione will be divided in two distinct layers, separated by a greenhouse gas buffer. In the upper layer, where temperature will be low, oxygen and nitrogen can be held for thousands of years. However, water vapors, if they make their way that far, will be lost into space. In the lower layer, even oxygen is nearly unstable. Water vapors will fast rise to the upper layer. Hydrogen, resulting from interaction between water molecules and ionizing radiation, will escape into space very fast. The good thing is that Dione lies in Saturn's magnetosphere and is protected from the solar wind. The atmosphere will look like this: Ground average temperature: 15 degrees C *Surface pressure at sea level: 1 *Atmosphere total mass (Earth = 1): 0.97 *Atmosphere breathable height: 497 km *Atmosphere total height: 1479 km Ground average temperature: 0 degrees C *Surface pressure at sea level: 1 *Atmosphere total mass (Earth = 1): 0.94 *Atmosphere breathable height: 386 km *Atmosphere total height: 1446 km Ground average temperature: -150 degrees C *Surface pressure at sea level: 1 *Atmosphere total mass (Earth = 1): 0.58 *Atmosphere breathable height: 355 km *Atmosphere total height: 1057 km Combined values (surface temperature = 0, above greenhouse layers temperature = -150) *Atmosphere total mass (Earth = 1): 0.76 *Atmosphere breathable height: 370 km *Atmosphere total height: 1251 km. Dione will have a very fluffy atmosphere, extending above one diameter. This is a major problem, because at that height, gravity is 1/4 compared to the surface. Less gravity will force the atmosphere to extend even further, becoming unstable within a human lifetime. In order to solve this problem, we have two choices: # Reduce surface temperature, which will decrease the speed of gas molecules # Reduce density, which will force the atmosphere to be more compact. We can reduce temperature down to water melting point (zero C). This is probably the lowest temperature which we can have if we want life to exist. However, a reduction from +15 to 0, will only decrease molecular speed by 5.2%. Reducing pressure will also have only limited effect. For Earth, reducing atmospheric pressure from 1 bar to 0.3 will be like taking all air out from sea level to the altitude of 8.4 km. The atmosphere will shrink with 8.4 km, from 25 to 16.6 km. In our simulation, this will remove 370 km of the atmosphere, to 881 km, a height that is relatively safe. In order to make this atmosphere breathable, we have to change composition. It will no longer have 80% nitrogen and 20% oxygen, but 80% oxygen and 20% nitrogen. The effect is that the air will be breathable just like on Earth. Side effects will be that airplanes will fly more difficult and with less nitrogen there will be less nitrates available for plants in the soil. Temperature Main article: Temperature. The first problem with Dione is that we need to gain the correct surface temperature. The Solar Constant is small (0.0209), compared to Earth (1.98). We will need Greenhouse Gases. The Greenhouse Calculator shows us that Dione will need 0.656 kg/sqm of sulfur hexafluoride for a temperature of 15 degrees C and 0.585 kg per square meter for 0 degrees C. Climate Simulation Main article: Climate. On Earth, the average temperature is +15 degrees C. Technicians will try their best to keep on Dione a surface temperature of 0 degrees C, because the atmosphere will not be stable at +15. Dione has a smaller diameter then Earth (0.088), so air currents can mix temperatures faster. The atmosphere will be high enough to pass over all Geographic barriers. However, with a more rarefied atmosphere, some differences might appear. Average temperatures for each latitude: At equinox: *poles: -0.6 C *75 deg: -0.3 C *60 deg: -0.2 C *45 deg: -0.1 C *30 deg: 0 C *15 deg: 0 C *equator: 0.1 C At winter solstice: *poles: -0.7 C *75 deg: -0.5 C *60 deg: -0.3 C *45 deg: -0.2 C *30 deg: -0.1 C *15 deg: -0.1 C *equator: 0 C At summer solstice: *poles: -0.1 C *75 deg: -0.1 C *60 deg: 0 C *45 deg: 0 C *30 deg: 0 C *15 deg: 0.1 C *equator: 0 C Day - night cycle variation: Dione has not a too long day day (2.737 Earth days) and is well protected by its greenhouse layer. So, temperature variations between day and night will not be significant. *Daily temperature variation: 0.6 degrees C *Equator day-night variations: **Equinox: -0.2 to 0.4 degrees C **Solstice: -0.3 to 0.3 degrees C *Day - night variations for 45 deg latitude: **Equinox: -0.4 to 0.0 degrees C **Winter solstice: -0.5 to 0.1 degrees C **Summer solstice: -0.3 to 0.3 degrees C Seasons: As seen above, Dione will have small, hardly noticeable seasons. But, as a whole, the climate will be a monoclime. Altitude variations: In this simulation, Dione will be heated until most of its crust will melt. As a result, the subsurface ocean will be exposed and Geographic features will change dramatically. There will be no high mountains, just some ice caps. Conclusion. Dione will have an average temperature of 0 degrees C or a bit lower (between -0.9 and +0.4). This will allow some of the ocean to be ice covered, letting settlers to have a solid surface. With so limited temperature variations, the air will tend to 100% saturation with moisture. This will cause clouds and hazes to permanently form. It might be raining or even snowing. However, because of no massive temperature variations, precipitations will be rare. With a low gravity, snow will need a long time to fall on the ground. Geography See also: Geography and Geographic Pattern - Craters. Dione has an interesting structure: a surface icy crust, a subsurface ocean and a central rocky core. Terraformers have 3 major ways to transform an icy Outer Planet: #Increase the heat, melt the ice and transform it into an Oceanic Planet, then leave it as it is. #If possible, build Artificial Continents after melting all the ice. #Use Ground Insulation, to save the icy crust, then cover it with solid rock. However, for Dione, the atmosphere forces us to something different. The icy crust will be melted, but not completely, exposing part of the ocean. The remaining crust will be used for settlers. The atmosphere is made of 86.3% oxygen and made up of 12.3 nitrogen. The rest is 1.3% is Methane, and hydrogen, and Argon. We don't know yet the composition of the new ocean. It might contain salts. In this case, the temperature must be set slightly below melting point of the oceanic water. We know that salt water melts at lower temperatures. Also, water exposed to an atmosphere with less pressure will melt at lower temperatures. Ice And Exposed Water: At the equator, temperature will be a bit higher then at the poles. Because of this, it is possible to have exposed ocean along the equator. On the other hand, at the poles, geological activity is supposed to be stronger, bringing heat to the surface. Because of this, it is highly possible that at the poles there will also be exposed water. Ice Shelf: Basically, Dione will have two large rings of ice along parallels 45, both in North and in South. It is unknown if the equatorial ocean or the polar oceans will be larger. Ice shelf will not be too deep, probably reaching at maximum 100 m. It will have many cracks and will not be safe for long trips. At its end, there will be a transition zone, with small floating icebergs. Ocean: The ocean will be very deep (roughly 165 km). At such depths, two different forces will fight. Gravity will try to separate water layers, based on salinity. At the same time, geothermal activity will bring heat from below and will break apart the stratification. Without temperature variations, there will be no winds and without winds there will be almost no waves. Conclusion: Dione will be a special type of oceanic planet, where settlers will live on floating ice. The Sky As any Outer Planet, Dione will have a lot of moisture in its atmosphere. Because of this, fogs and clouds will be common. Probably the atmosphere will never be clean enough to see even a corner of blue sky. Still, from orbit, some celestial bodies will be visible. The Sun will appear 0.97 units wide (like an object 0.97 mm wide will appear if you look from a distance of 1 m, see Angular Size for details). Saturn and other satellites visible as disks will be: *Saturn - 309 units *Mimas - 0.71 to 2.06 units *Enceladus - 0.82 to 3.63 units *Tethys - 1.58 to 12.95 units *Rhea - 1.69 to 10.18 units *Titan - 3.22 to 6.09 units *Iapetus - 0.37 to 0.46 units Some planets will also be visible: *Mercury: 4.6 to 4.8 *Venus: 1.7 to 2.0 *Earth: 2.9 to 3.4 *Mars: 5.9 to >6 *Jupiter: -0.2 to 2.4 However, people from the surface will not see this, unless they fly into outer space. Human Colonies *Population limit: 0.43 million *Land population feeding capacity: 3.3 people fed from one square km *Largest city supported by environment: 1 700 people Assuming it will have similar types of terrain Earth will have, Dione can support a Population Limit of 0.43 million people. An outer planet is in a critical balance. An increase of heat form the surface can result in a hole in the greenhouse layer. This is why population limit is calculated to be so small. For Dione, where a slightly change of temperature can result in an increase or decrease of the ice shelf, maintaining the proper temperature is very important. Industry Dione will be an oceanic world. We can imagine submarines searching deep into the ocean and mining the salts dissolved there. But, more important, Dione will be an ideal place for arctic and Antarctic organisms, which on Earth are endangered. Dione can produce furs and by-products of like whale oil, which are now prohibited on Earth. The main source of energy will be nuclear. Agriculture On the surface of the ice, mammals and birds will rest. This will include penguins, polar bears and seals. The ocean will contain fish, whales and algae. The main source of food will come from hunting and fishing. Also, these activities will support a local industry that can support exports. Transportation The ice will have many cracks, so establishing roads is not an option. The ocean can be navigable, but there will always be icebergs roaming around. Close to the border of the shelf, there will be a narrow sheet of ice that will pose a thread to sailors. The best option for transportation will be by air. This will be used primarily for people. Also, there will be boats and ships sailing on the ocean and snowmobiles running on the ice. Another, challenging way to travel, will be the submarine, which can pass below any ice shelf to reach a town almost anywhere. This should be very efficient for cargo. Around each town, there will be docking places for submarines. Since Dione is tidal locked, there is no place for geosynchronous satellites. Still, there are a few safe orbits around the moon for satellites that will provide telecommunications. The large atmosphere will pose major challenges for radio waves. There will be constructed at least one base on the surface, for space travel. Big ships will not be allowed to land, because their weight can crack the ice shelf. Large interplanetary ships, carrying passengers and cargo to and from Saturn, will dock at Helene. Then, smaller ships will ferry between the little moon Helene and Dione. Tourism Dione will be interesting because it will host polar wild life. Ecologists, biologists and tourists will come to see with their own eyes how arctic and Antarctic species, endangered on Earth, can live and breed here. Because of the low temperatures, Dione will not pose severe threads to human health. Moisture in the air will be around 100%, but inside homes, where the atmosphere will be artificially heated, humidity will decrease fast. Wild Life This is perhaps the most interesting aspect of terraforming Dione. Because the moon hardly can support its atmosphere, we had to decrease temperature and pressure. This creates the perfect environment both for Arctic and Antarctic species. It is something that came unexpected. Animals and birds can stay on ice, but they need some solid rock to breed, lay eggs and grow their babies. Also, whales, dolphins and many fish populations need some solid ground. For this reason, settlers will have to build some floating islands and some floating reefs. Category:Simulation Category:Math